Astronomical Associations of "The Day of the Dead"

Just as the celebration of the Virgin of Guadalupe can be traced to the pre-Conquest festival honoring
the Nahua sun goddess Tonantzin at the winter solstice (December 12 in the Julian calendar), so too,
may we discern the origins of the "Day of the Dead" in the Nahua ritual known as "the binding of the
years". Although the astronomical event which specifically provided the timing for the latter was the
zenithal passage of the Pleiades at midnight every 52 years (a year known as "2 Reed" in the Nahua
calendar), there is the strong likelihood that the "Day of the Dead" represents an annual celebration
whose original purpose was to commemorate the same celestial event.

To be sure, the most immediate objections to such an hypothesis will be raised by those who would
argue that the Mexican celebration of the "Day of the Dead" is simply an indigenous version of
"All Saints Day" (November 1) and "All Souls Day" (November 2) introduced by the Spanish.
Tempting as such an explanation may be, it does not accord with the facts. We know that other
cultures in widely separated regions of the world also celebrated festivals honoring the dead, so the
roots for such a practice are very ancient and diverse indeed. The Egyptians, for example, had a
festival honoring Osiris, the god of the dead, at least a couple millenia before the beginning of the
Christian era, though its timing seems to have been related to the winter solstice (December 22). The
ancient Druids in Celtic society had a similar festival held on October 31 -- the beginning of their
New Year -- which has come down to us as "Halloween". And while the early Roman church
began celebrating the death of its martyrs shortly after the triumph of Christianity, it was not until
the papacy of Pope Gregory III (i.e., 731-741) that "All Saints Day" was officially moved to
November 1. Moreover, it was not until about three centuries later that the Abbot Odela of Cluny
added "All Souls Day" to the Christian calendar, chosing November 2 for its celebration. Thus,
unless we are willing to accept the notion that the Roman church may have "borrowed" its date
for commemorating the dead from the Celts, we already have a striking coincidence in timing
between these two cultures, not to mention that which exists between the Christian and the Nahua

Ironically, it was only a matter of about three decades after Pope Gregory had shifted the holiday
honoring Christian martyrs to November 1 that the Nahua peoples of the Mexican plateau came up
with their own festival commemorating the dead. (This was the Toltec version of the Mesoamerican
calendars whose origin I have traced in my book to the year 778.) Because their sacred count of
260 days and their secular calendar of 365 came back into phase with each other only every 52 years,
this correspondence led them to commemorate the beginning of each new cycle with a ceremony
known as "the binding of the years". Though its astronomical basis was the zenithal passage of the
Pleiades at midnight, as mentioned above, the latter was an event which recurs each year in late
October-early November. Because of the imperfections in their time-counts, such an event could
not be expected to recur on a day of the same number and name each year. On the other hand, there
was a very specific way to mark this event astronomically -- indeed, it was a technique whose
origins went back to that of the 260-day sacred almanac itself.

At least as early as 800 B.C. and, more likely as early as 1000 B.C. -- judging from evidence at
Teopantecuanitlán, the Mesoamericans had realized that they could calibrate the beginning date of
their sacred almanac (August 13) anywhere within their homeland, even though the original fixing
of that event took place only with the zenithal passage of the sun over Izapa in the far south of Mexico.
This could be done simply by counting 52 days following the summer solstice and marking the
position of the setting sun against the horizon. Because they lacked any means of carefully defining
angular measurements, they employed constructed artifacts (such as pyramids or the alignment of
streets) in such locations to mark the resulting azimuths. It is these alignments which occur
throughout the Mesoamerican cultural realm and whose average azimuth measures 285.5º
(Illustrations from Teotihuacán and Tikal, amongst others, I have explained earlier.)

To pin down the date in their calendar which would correspond to that of November 1 in the
Gregorian calendar the Mesoamericans had merely to reverse the process described above. By
marking where on the horizon the sun rose 52 days ahead of the winter solstice, they would be
defining the azimuthal reciprocal of the August 13 sunset; in other words, they were identifying
an azimuth of 105.5º, because on November 1 the sun reaches a latitude in the southern hemisphere
(14.7º) which is directly equivalent to the latitude of Izapa in the northern hemisphere. (Of course,
the sun returns to the same latitude 52 days after the winter solstice as well, and thus rises at the
same azimuth once more. This event takes place on the equivalent of February 12 in the Gregorian
calendar, a date which Sahagún identified as the beginning of the Aztec year. In an earlier article I
have shown that this azimuth was also built into the "observatory" constructed at Chalchihuites
near the Tropic of Cancer, most likely by the Toltecs in the ninth or tenth century.) Less than a
quarter hour after midnight the same day the Pleiades passed through the zenith above Tula and/or
Tenochtitlán. Is it just another striking coincidence that the major festivities of "the Day of the Dead"
are timed to begin about midnight? Or do we witness in this popular Mexican tradition another
cultural carry-over from the pre-Columbian past? (For a more detailed examination of this subject,
the reader is referred to the paper by Johanna Broda titled "Astronomical Knowledge, Calendrics,
and Sacred Geography" in Astronomies and Cultures, edited by C.L.N. Ruggles and N.J.
Saunders, and published by the University Press of Colorado in 1993.)


(Note that references for this and the other papers are found on the 'home page' of this article.)

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